ci: Drop support for Node.js 14 (#5835)

Node.js 14 goes EOL on 2023-04-30, and support for it should be dropped.
https://github.com/nodejs/Release#release-schedule

.github/workflows/ci-master.yml

@@ -13,7 +13,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [14.x, 16.x]
+        node-version: [16.x]
 
     steps:
       - uses: actions/checkout@v3

.github/workflows/e2e-tests.yml

@@ -51,22 +51,10 @@ jobs:
     secrets:
       CYPRESS_RECORD_KEY: ${{ secrets.CYPRESS_RECORD_KEY }}
 
-  run-e2e-tests-node-14:
-    name: E2E [Electron/Node 14]
-    uses: ./.github/workflows/e2e-reusable.yml
-    if: ${{ github.event_name == 'schedule' }}
-    with:
-      branch: ${{ github.event.inputs.branch || 'master' }}
-      user: ${{ github.event.inputs.user || 'schedule' }}
-      spec: ${{ github.event.inputs.spec || 'e2e/*' }}
-      run-env: base:14.21.1
-    secrets:
-      CYPRESS_RECORD_KEY: ${{ secrets.CYPRESS_RECORD_KEY }}
-
   calls-success-url-notify:
     name: Calls success URL and notifies
     runs-on: ubuntu-latest
-    needs: [run-e2e-tests, run-e2e-tests-node-14]
+    needs: [run-e2e-tests]
     if: ${{ github.event.inputs.success-url != '' }}
     steps:
       - name: Notify Slack on failure